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Evidence on the Dual Nature of Aluminum in the Calcium‐Silicate‐Hydrates Based on Atomistic Simulations
Author(s) -
Abdolhosseini Qomi Mohammad Javad,
Ulm FranzJosef,
Pellenq Roland J.M.
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2011.05058.x
Subject(s) - calcium silicate hydrate , silicate , calcium silicate , materials science , chemical engineering , hydrate , aluminate , solid state nuclear magnetic resonance , aluminium , mineralogy , composite material , chemistry , cement , organic chemistry , nuclear magnetic resonance , physics , engineering
Hydration of tri‐calcium silicate ( C 3 S ) and di‐calcium silicate ( C 2 S ) precipitates calcium‐silicate‐hydrate ( CSH ) which is the bonding phase responsible for the strength of cementitious materials. Substitution of part of C 3 S and C 2 S with aluminum‐containing additives alters the chemical composition of hydration products by precipitating calcium‐aluminate‐silicate‐hydrate ( CASH ). Incorporation of aluminum in the molecular building blocks of CSH entails structural and chemo‐mechanical consequences. These alterations can be measured through solid state nuclear magnetic resonance ( NMR ) experiments. By conducting a wide spectrum of atomistic simulation methods on thousands of aluminum‐containing molecular CASH structures, an overall molecular approach for determination of CASH nanostructure is presented. Through detailed analysis of different order parameters, it is found that aluminum can exhibit a tetra‐/penta‐/octahedral behavior which is fully consistent with the recent NMR observations. This corresponds to the formation of a class of complex three‐dimensional alumino‐silicate skeletons with partial healing effect in the CASH nanostructure potentially increasing durability and strength of hydration products. We explored the variation of mechanical observables by increasing aluminum content in CASH structures of varying calcium to silicon ratio. Finally, deformation of CSH s and CASH s of different chemical formula in a multi‐scale fashion unravels the effect of chemical composition on the strength and kinematics of deformation in this particular type of composites.